1. Field of the Invention
This invention relates to a semiconductor integrated circuit device and a manufacturing method thereof, and more particularly to a semiconductor integrated circuit device having an electrically rewritable nonvolatile semiconductor memory device, and a manufacturing method thereof.
2. Description of the Related Art
A voltage is kept applied to a resistor element used in a timing circuit of an electrically rewritable nonvolatile semiconductor memory device, for example, a NAND flash memory at the standby time. Therefore, it is necessary to increase the resistance value. This is because it is desired to reduce a standby current.
The method for forming the resistor elements is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-110825 and Jpn. Pat. Appln. KOKAI Publication No. 2002-110827. According to Jpn. Pat. Appln. KOKAI Publication No. 2002-110825, the conductive layer used as a control gate is used as the resistor element. Further, according to Jpn. Pat. Appln. KOKAI Publication No. 2002-110827, first and second conductive layers used as a floating gate and a third conductive layer used as a control gate are used as the resistor element.
As is described in Jpn. Pat. Appln. KOKAI Publication No. 2002-110825 and Jpn. Pat. Appln. KOKAI Publication No. 2002-110827, a gate material is used to form the resistor element. The gate material is used as a gate, and therefore, it is desired to lower the resistance value. On the other hand, as described before, it is desired to increase the resistance value of the resistor element.
Thus, there are provided mutually conflicting requirements for the gate and resistor element.